Kenwood TS-850S Replacement Manual

TS-850S REPLACEMENT OF D31 AND D4-D5-D6
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Symptoms:
D31 FAILED: No or low receive and/or transmit. High pitched tone in speaker. RXB showing
more than 0 volts in transmit or TXB showing more than 0 volts in receive.
D4, D5 AND/OR D6 FAILED: "Suck out" of RX signal and or TX output on one or more
bands.
Fix: Replace affected components on opposite side of RF unit board. These are all type RLS-135
diode. No substitutes are recommended.
Remove power cable and covers of rig. Invert rig. Remove the shiny cover near the rear of the
RF unit (left hand board as rig faces you). Remove the flex connectors on the side of the board
leading to the IF unit. Remove other coax connectors as needed; MARK THEM to ensure that
they go back in the right places. You should be able to fold the board toward you and then to the
right side of the rig to work on the back side of the board.
Refer to Fig. 1 for location and orientation of the board.
Fig. 1 LOCATION OF
RF UNIT
RF unit is on the left side
of the bottom of the rig
as it faces you.
or damage due to the use or misuse of this information.
FIG. 2 LOCATION
OF D31 ON RF
UNIT
Next, using Fig. 2, located D31.
Using a GROUNDED temperature-
controlled soldering iron and some
de-soldering wick, remove the solder
from both ends of the diode. With the